Japanese Patent No. 3613665 describes a known device that boosts suction noise. The device described therein is for amplifying suction noise and has plural intake ducts having resonance frequencies that are different from each other, so that it is possible to boost the suction noise at different frequencies, and permits introduction of suction noise into the vehicle passenger compartment.
However, the device for amplifying suction noise described in Japanese Patent No. 3613665 has some disadvantages. First, because the device is constituted with plural intake ducts, there is no leeway in the space required inside the engine compartment. Thus, there are restrictions on the layout, and the device is difficult to install in the engine compartment.